If there was no nondeductible traditional IRA contribution made for 2022 or any prior year that created $6,000 of basis that carried into 2023 (and you did not acquire any such basis from any other source such as the rollover of after-tax funds from an employer plan), line 2 should have been blank. But that then raises the question, how did you have $12,000 in a traditional IRA to convert? Was the other $6,000 pre-tax money from, say, a deductible traditional IRA contribution made in a prior year?
